In order for conveyor lines at food processing, material handling, manufacturing and other types of plants to function efficiently, each worker on the assembly line must be able to accomplish his task with essentially the same speed and accuracy as his co-workers. However, the productive output of workers on conveyor lines may be affected by the height of the worker. For example, a short worker may have a limited reach across a conveyor belt and, thus, may have to exert more effort than a tall worker to access material carried by the conveyor belt. Consequently, the shorter worker may tire more quickly or, more significantly, strain muscles from exertion. This physical strain tends to reduce individual productivity which can translate into a reduction of overall plant productivity. Moreover, the physical stress of the job may lead to worker discontentment and a high turn-over rate for employees.
In addition to the above-mentioned problem, the line of vision of a short worker is not as encompassing as that of a tall worker. So, a short worker responsible for quality control may not detect defective products carried by the conveyor belt as readily as a tall worker.
A temporary solution to the above described difficulties is for a shorter worker to stand on a relatively sturdy box, crate or the like placed adjacent the assembly line. Although crates offer an immediate height adjustment, the crates are typically not secured to a ground surface and, consequently, may topple over if a worker shifts his weight. This can lead to worker injuries. Moreover, such make-shift solutions to height adjustment rarely position the worker at precisely the best or optimum height for his or her stature.
In an attempt to reduce the potentially hazardous use of temporarily placed crates, some conveyor assembly lines have installed vertically adjustable step assemblies at each work site. These step assemblies generally include a step frame which can be selectively hooked or attached at various heights to the conveyor support framework, for example, by hooking the platform step to the appropriate apertures in the conveyor framework. Although such step assemblies are not subject to tipping, the assemblies may only be positioned at a fixed number of levels and do not provide a continuum of possible vertical positions. Consequently, only a limited range of workers actually benefit from installation of these permanently fixed step assemblies.
In order to accommodate a broader height range of workers, conveyor belts also have been positioned on a sloped floor surfaces. A worker may then choose a working site along a conveyor belt from a continuous range of positions. However, the structural design of a sloped working floor is somewhat impractical and does not accommodate many possible combinations of the height distributions in the work place.
Accordingly, it is therefore a general object of the invention to provide a vertically adjustable work station assembly which will obviate or minimize difficulties of the type previously described.
It is a specific object of the invention to provide a continuously vertically adjustable work station assembly which may be used to elevate a person to an optimum working height.
It is another object of the invention to provide a vertically adjustable work station assembly which accommodates a wide height range of persons and, thus, may be effectively used by any number of persons.
It is still another object of the invention to provide a vertically adjustable work station assembly which is easy to operate, durable, compact, has a minimum number of parts, is economical to construct and can be retrofit for use with a wide range of conveyor lines.